Nitrogen electrode reaction has been investigated in a LiBr-KBr-CsBr melt containing Li3N. The reaction N3- → 1/2N2 + 3e- is confirmed by quantitative analysis of anodically evolved gas. The Nernst relation holds for the rest potential of Ni electrodes at a nitrogen gas pressure, pN2, of 0.05-1.0 atm and an anion fraction of the N3- ions, xN3-, of 0.003-0.010 (anion fraction). Then, the standard formal potential of the N2/N3- couple, EN2/N3-′, is evaluated to be 0.251 ± 0.009 V versus Li+/Li (pN2 = 1 atm, xN3 = 1) at 673 K. The dependence of EN2/N3-′ on the temperature (570-730 K) gives a linear relation, whose slope is (-0.930 ± 0.117) × 10-3 V K-1. Thermodynamic quantities for the formation of Li3N in the melt are also estimated.
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